Showing papers on "Dengue virus published in 1974"

The use of mosquitoes to detect and propagate dengue viruses.

Abstract: Parenteral inoculation of Aedes albopictus mosquitoes was found to be a much more sensitive method to detect dengue viruses than was plaque assay in LLC-MK2 cells—the most sensitive dengue isolation system known heretofore. This was true whether the viruses were present in sera from naturally infected humans or had been “adapted” to LLC-MK2 cells or newborn mice. Male mosquitoes were as susceptible to infection as females and could be used without the safety precautions necessary for the latter. All four types of dengue virus replicated to high titer in both male and female mosquitoes and high titered pools of virus could be prepared from these insects without the possible modifying effects of “adaptation” to cell cultures or mice.

Fatal hemorrhagic disease and shock associated with primary dengue infection on a Pacific Island.

Abstract: An epidemic of dengue type 2 which occurred on Niue Island during the first half of 1972 involved approximately 90% of the population of 4,600 persons and affected all age groups equally. Serologic data indicated that this was the first occurrence of any dengue virus on the island for at least 25 years. Many persons had minor hemorrhages associated with febrile illnesses during the outbreak and a few had severe hemorrhages or shock. Twelve deaths occurred which may have been caused by dengue. The clinical features of the fatal illnesses among children were very similar to those described previously for dengue hemorrhagic fever or dengue shock syndrome. It is concluded that at least some deaths among children were caused by dengue virus and were, consequently, the result of primary infection with that virus.

Etiologies of the Experimental Dengues of Siler and Simmons

Abstract: Four participants in the American Army Philippine dengue (d) studies of Siler (1924-25) and five subjects from the studies of Simmons (1929-30) were bled 42 to 48 years after experimental infection. Sera were studied by hemagglutination-inhibition, complement-fixation and plaque reduction neutralization (PRNT) tests for antibodies to the known viral causes of the dengue syndrome in Asia and to St. Louis encephalitis virus. PRNT tests were done with and without fresh normal human serum (accessory factor). Serum from one of four Siler study volunteers had unequivocal evidence of only a previous d4 infection; the remainder had broadly reactive group B antibodies, including d4, suggesting past infection with two or more different dengue viruses. Sera from four of the Simmons study group had high-titered PRNT antibodies to d1 and the remaining serum had d1 antibody when accessory factor was added. In three sera there was monotypic PRNT antibody to d1. Acessory factor increased PRNT titers, particularly to d1 virus in the Simmons group. Only sera with antibody patterns suggesting past infections with two or more dengue viruses had high levels of SLE PRNT antibody. It is concluded that d4 was transmitted in the 1924 to 1925 and d1 in the 1929 to 1930 experiments. Notable differences in clinical features of dengue infections in the two studies suggest the possibility of the existence of an unique spectrum of responses to infection with different dengue virus type.

Cross-protection between group B arboviruses: resistance in mice to Japanese B encephalitis and St. Louis encephalitis viruses induced by Dengue virus immunization.

Abstract: Albino Swiss mice, immunized with any of several types and strains of dengue viruses, were afforded substantial protection against peripheral Japanese B encephalitis or St. Louis encephalitis virus challenge. Dengue-2 (New Guinea “C”)-immunized mice showed, 10 and 20 weeks after immunization, undiminished resistance with concomitant cyclophosphamide treatment and virus challenge. Examination of the effects of immunization on Japanese B encephalitis virus pathogenesis, after virus challenge with concomitant cyclophosphamide treatment, indicated that protection was associated with decreased viremia and virtually no virus replication in the brain as compared with controls. These effects could be demonstrated before detection of any neutralizing antibody to the challenge virus. From the applied aspect, the data support the hypothesis, based on epidemiological evidence and experiments in hamsters, that prior exposure of man to dengue viruses can confer some degree of protection against Japanese B encephalitis or St. Louis encephalitis disease.

Seroepidemiologic study of arbovirus infections in the north-east and south of Thailand.

Abstract: Blood specimens were collected from villagers in Khon-Kaen province, in the north-eastern region, and in Songkhla province, in the southern region of Thailand in the pre- and post-epidemic seasons of hemorrhagic fever. The hemagglutination inhibition antibody titers of the specimens were measured against dengue virus type 2, type 4, Japanese encephalitis virus and chikungunya virus. In general, Khon-Kaen villagers showed higher levels of HI antibodies against these arboviruses than Songkhla villagers and in both areas the antibody level against chikungunya virus, a group A arbovirus, was usually much lower than those against group B arboviruses. Specimens from Khon-Kaen province had such high antibody positive rates for group B arboviruses (80-100%) from an early age (3-4 years), in the pre-epidemic season, that scarcely any increase in the positive rate was observed in the post-epidemic season. The positive rate in specimens from Songkhla province was not so high in the pre-epidemic season and some increase was seen in the post-epidemic season, especially in lower age groups (3-4 to 7-9 years). The patterns of HI antibody titers in different age groups in the Khon-Kaen and Songkhla provinces were also compared. The patterns changed with increase of ages and were also different with different viruses. The patterns for chikungunya virus were quite different from those for dengue type 2, type 4 and Japanese encephalitis virus. These results suggest that people in Khon-Kaen are exposed to group B arbovirus infections more often in childhood and attain high antibody levels more rapidly than people in Songkhla.

Arbovirus infections in sarawak: serological studies in man

Abstract: 1. 1.2,118 human sera collected from all age groups in a wide variety of ecological zones in Sarawak during December 1962 and January 1963, April-May 1964 and September-December 1966, were tested for haemagglutination-inhibiting and neutralizing antibodies to 9 arboviruses. 2. 2.Japanese encephalitis and dengue virus antibodies were prevalent in all areas. The estimated annual infection rate with Japanese encephalitis virus varied from about 2% to over 9% with a mean of 6%. Estimated dengue virus infection rates varied from less than 1 % to over 11% with a mean of just over 5% per annum. 3. 3.There was only slight evidence of infection with group A, Bunyamwera and other group B arboviruses. 4. 4.No significant differences in the prevalence of arbovirus infections could be distinguished between any of the ecological zones. The wide distribution of Japanese encephalitis and dengue virus infections matched the distribution of the principal arthropod hosts of the viruses, C. tritaeniorhynchus, C. gelidus and Ae. albopictus . 5. 5.The general trend of arbovirus infections in Sarawak was of highest infection rates in coastal, estuarine and inland forest areas. Urban areas had the lowest rates while rural areas of settled cultivation had intermediate rates of infection.

Dengue type 3 infection in Panama.

Abstract: Reexamination of sera collected in Panama in 1954 by a plaque-reduction neutralization procedure indicated that dengue type 3, as well as dengue type 2, infection had occurred in that area between 1941 and 1954.

Establishment of an 'in vitro' Model of Dengue Infection for the Study of Immunologic Events in this Disease

Abstract: : Pathologic studies have shown that dengue virus replicates in organs rich in lymphocytic tissues. Studies in vitro with monkey lymphocytes demonstrated that viral replication is dependent upon blast transformation. Therefore the replication of dengue-2 virus in three human lymphoblastoid cell lines of B cell characteristics in continuous culture (Raji, 8866, Wil 2WT) and in human peripheral lymphocytes (HPL) stimulated by mitogens was studied. Dengue-2 virus (SEATO strain) readily replicated in the three human lymphoblastoid cell lines without apparent effect on the host cells. Persistently infected cells produced virus for at least five months. The kinetics of the infection and the localization of the dengue antigens were studied by immunofluorescence and electron microscopy. Persistently infected Raji cells expressing viral antigens on their surface formed rosettes with normal human T lymphocytes and bound human platelets in the presence of human antibody to dengue virus. Immune complexes in sera of patients with dengue could be demonstrated and serum enzyme inhibitors were depressed.